Passive devices perform important functions in an electronic system. Recently, the making of miniaturized, multi-functional, and economical electronic appliances has become popular, and is giving rise to requirements for passive devices to be fabricated in the form of an array, a network, and a built-in passive device. Such passive devices sense, monitor, transmit, reduce, and control voltage.
Resistors as passive devices suppress a flow of electric charge or current, thereby controlling the amount of current. Such passive devices may be classified as a thin film resistor, in which a metal layer is thinly deposited to form a pattern, and an active layer resistor in an active area. Thin film resistors are generally disposed between metal lines in a semiconductor device.
FIG. 1 is a cross-sectional view of a conventional semiconductor device including metal patterns and a thin film resistance pattern. The semiconductor device of FIG. 1 includes a semiconductor substrate 10, a first dielectric 20 on the substrate 10, a lower metal line 30 on the first dielectric 20, and metal patterns 40. Also, a second dielectric 50, a thin film resistor pattern 60, and a third dielectric 70 may be formed over the metal patterns 40, and an upper metal line 80, and a via 90 may be successively formed over the lower metal line 30 and over or adjacent to the metal patterns 40.
As described above, in the process of manufacturing the semiconductor device, the thin film resistor pattern 60 may have a nonuniform profile, width, or shape due to the presence of the metal patterns 40 under some portions of the thin film resistor pattern 60, and the absence of the metal patterns 40 under other portions of the thin film resistor pattern 60. That is, in an exposure process performed on a photoresist material for patterning a thin film resistor material and forming the thin film resistor pattern 60, a portion of the light may be transmitted through the thin film resistor material due to a thinness of the thin film resistor. The transmitted light is reflected by the metal patterns 40 located under the thin film resistor back to the photoresist over the thin film resistor material during the exposure process, and thus forming a photoresist pattern that has some relatively wide portions. The photoresist pattern is then used to pattern the thin film resistor material and form the thin film resistor pattern 60. As a result, a profile of the thin film resistor pattern 60 may be deformed.
FIG. 2 is an overhead photograph of a thin film resistor pattern formed according to the conventional manufacturing method described above. The photograph shows that a portion of the thin film resistor pattern formed in an area that contains underlying metal patterns has a uniform width, but the thin film resistor pattern disposed in an area that does not contain underlying metal patterns is reduced in width.
That is, referring to FIGS. 1 and 2, in the conventional method of manufacturing the semiconductor device including the metal patterns and the thin film resistor pattern, it may be difficult to form a thin film resistor pattern having a uniform profile. As a result, a resistance of the thin film resistor may be different from that desired by a designer.